Gangland - Season 4

The Avenues are one of the most powerful Hispanic street gangs of Los Angeles.

The Pagans gang, which originated in Maryland during the 1950s and has grown to 44 chapters with more than 900 members spread along the East Coast, is considered a major dealer in the methamphetamine trade.

The Latin Kings, regarded as the largest and most brutal Latino gang in the United States, traces its roots to 1940s Chicago.

The Best Friends, a gang of ruthless contract killers, have stalked the east side of Detroit since 1985 and have been linked to more than 80 murders, according to federal officials.

The Love Murdering Gangsters (LMG) formed by drug dealers and killers in Memphis, Tenn., is regarded as the most notorious gang in the Mississippi Delta.

St. Louis is home to an estimated 10,000 gang members, including the notorious Boys of Destruction gang.

Started as a means of survival, the white supremacist Aryan Brotherhood is the largest prison gang in Texas, and it is spreading to the suburbs of Dallas.

The Sons of Silence, Colorado's largest motorcycle gang, has spread to 36 chapters throughout the world since its inception in the 1960s; undercover agents infiltrate the gang.

Authorities form a task force in 2003 to take down the Hidden Valley Kings, a gang controlling the drug trade in Charlotte, N.C.

The Hoover Criminals, whose members call themselves "Everybody Killers," become a nightmare for Portland, Ore., after moving there from Los Angeles during the 1980s to capitalize on the drug trade.

The prison gang Dead Man Incorporated has become the biggest threat in the Maryland penal system, grown to 14,000 members within a decade and spread across the country.

Two outlaw motorcycle gangs, the Mongols and Hells Angels, are entrenched in a brutal turf war over California.